To get your ultimate high-performance body, try the secret weapon of models and Olympians: the Redcord workout.

This time, though, I was indoors, at Pilates on Fifth in Manhattan, strapped into a contraption with lipstick-red ropes and slings hanging from the ceiling. The setup resembled a sleekly designed medieval torture chamber, but I wasn't deterred: I've done my time in the gym. I can out-rep (usually) and outrun (at times) most. Yet I found myself flat on my back, legs splayed, at a loss, as my trainer asked me to lift my hips off the ground.

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"Lift? With what?" This was my first attempt at Redcord, the Norwegian workout offered in more than 80 percent of gyms in Norway and a favorite of Swedish models. Not that I'm expecting to get Elin Nordegren's physique, but the fact that the latest fitness import is a go-to for top athletes who've trained on it at the U.S. Olympic Training Center in Lake Placid, New York, means it's no joke.

At least in my total initial failure, I was in good company. "The first time I tried it, I did only five reps," confesses Sara Studebaker, America's top-ranked biathlete, with a laugh. According to her trainer, Peter Toohey, "Every Olympian, the strongest, the fastest — they all fail on the system initially. Guaranteed."

The reason, explains Redcord guru Michael Torres, is that most exercises let us cheat. It's easy to churn out reps without engaging our core or using a stronger side to compensate for a weaker one. Over time, the neglected muscles weaken and can't respond when the brain signals them to move. When life throws us a curveball like a wet sidewalk, which requires a strong core to avoid injury, our brain screams, "Help!" but our muscles are too slow to respond. Redcord sharpens the brain-body connection.

For a gymnast, Redcord can target the muscles needed to stick tricky landings. For a skier, it can diagnose if one side is weaker to smooth out turns and jumps. (For the average person, it can also be used for rehab post-injury or for chronic pain.)

Personally, I was after stronger abs and a better butt. So we stuck with the basics, like a squat while attached to various pulleys. Easier said than done: With one ankle looped comically behind me, my arms strapped above me, the ropes shook uncontrollably. I persevered for the next few weeks, working out parts of my body I had naively thought were already in shape.

I thought I knew proper push-up form. With Redcord, we refined my technique so that I was working exactly the right muscles, with a bungee slung under my belly for assistance. As I got stronger, Torres lowered the bungees, until eventually I was almost doing a perfect push-up without any help at all. Improvement comes from doing more reps and repositioning the cords.

By my fifth session, I succeeded in repeating the initial butt-lifting exercise with far less rope-quivering. For fun, I tried the "Mission Impossible" — a move in which each limb is suspended by a rope, and, in my case, the core is supported by a sling. First, I balled up, knees to elbows. Then I busted out my arms and legs into an X, like Tom Cruise (in theory). I'm told that the exercise literally uses every muscle — and while my brain doesn't yet comprehend where each of them are exactly, I'm tapping into them all, simply by trying to keep the ropes still. It's the kind of exercise normally done by an elite soccer player looking to nail midair bicycle kicks. Perhaps one day I'll do one of those — or not. For now, I'm happy to walk taller, feel stronger, and make it down the block confident that I can manage just about any curveball life throws at me.